Question

without finding the square, evaluate 20² – 1​

Answer 1

Answer:

399

Step-by-step explanation:

Given,

${20}^{2} - 1$

also

${20}^{2} - {1}^{2}$

Since,

${x}^{2} - {y }^{2} = (x + y)(x - y)$

Hence,

$= (20 + 1)(20 - 1)$

= 21 × 19

= 399 (Ans)